首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   380453篇
  免费   24941篇
  国内免费   2828篇
耳鼻咽喉   5227篇
儿科学   8268篇
妇产科学   10114篇
基础医学   53464篇
口腔科学   11829篇
临床医学   30197篇
内科学   78784篇
皮肤病学   8584篇
神经病学   27325篇
特种医学   13967篇
外国民族医学   82篇
外科学   60942篇
综合类   9972篇
现状与发展   1篇
一般理论   64篇
预防医学   17507篇
眼科学   9457篇
药学   31134篇
  1篇
中国医学   2194篇
肿瘤学   29109篇
  2021年   2654篇
  2019年   2737篇
  2018年   4557篇
  2017年   3452篇
  2016年   3571篇
  2015年   4052篇
  2014年   5735篇
  2013年   7434篇
  2012年   10125篇
  2011年   10322篇
  2010年   6252篇
  2009年   5893篇
  2008年   9561篇
  2007年   10407篇
  2006年   10313篇
  2005年   9363篇
  2004年   8887篇
  2003年   8617篇
  2002年   8302篇
  2001年   28324篇
  2000年   28842篇
  1999年   23715篇
  1998年   5180篇
  1997年   4269篇
  1996年   3859篇
  1995年   3504篇
  1994年   3126篇
  1993年   2859篇
  1992年   16084篇
  1991年   14849篇
  1990年   14191篇
  1989年   13989篇
  1988年   12624篇
  1987年   12087篇
  1986年   11125篇
  1985年   10356篇
  1984年   6929篇
  1983年   5609篇
  1982年   2724篇
  1979年   5487篇
  1978年   3350篇
  1977年   2974篇
  1975年   2645篇
  1974年   3071篇
  1973年   2870篇
  1972年   2832篇
  1971年   2781篇
  1970年   2519篇
  1969年   2550篇
  1968年   2260篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Abstract

This study was undertaken to compare the concentrations of pro- and anti-angiogenic growth factors, nitric oxide (NO) stable metabolites in maternal serum and embryonic left ventricular (LV) isovolumic relaxation time (IRT, ms) during the first trimester in two groups of women: with pregnancy conceived by assisted reproductive technologies (ART, n?=?39) and normally conceived (control group, n?=?68) pregnancy. The concentration of vasoconstrictor endothelin 1 was 45.5 times more in ART than in control group. On the contrary, the concentrations of NO stable metabolites in ART were 1.9 times less than in control women. The assessment of angiogenic suppressors in ART women demonstrates the decrease in s-endoglin concentration was 1.6 times and in soluble receptor to vascular endothelial growth factor concentration was 2.0 times in comparison with control group. There was a significant increase in LV IRT in ART embryos in comparison to control ones. These data suggest significant changes in pro- anti-angiogenic factors balance and increase in vascular impedance in ART-conceived embryos.  相似文献   
52.
53.
Digestive Diseases and Sciences - To determine whether the presence of portal vein thrombosis (PVT) where venous flow within the liver may be altered may delay the diagnosis of HCC and be...  相似文献   
54.
55.
ABSTRACT

Purpose

To investigate the effect of 1% tropicamide on anterior chamber aqueous flare (ACAF) measurements acquired with laser flare meter in patients with pseudoexfoliation.  相似文献   
56.
57.
International Journal of Legal Medicine - Sex identification is a primary step in forensic analysis of skeletal remains. The accuracy of sex estimation methods greatly depends on the sexual...  相似文献   
58.
59.
Inflammation, an important contributory factor of muscle and bone aging, is potentially modulated by diet. This study examined the associations of dietary inflammatory index (DII) score with musculoskeletal parameters and related disease outcomes in 3995 community-dwelling Chinese men and women aged ≥65 years in Hong Kong. DII score at baseline was estimated from a food frequency questionnaire. Bone mineral density (BMD) and muscle mass estimated by dual-energy X-ray absorptiometry (DXA), hand grip strength, gait speed, and chair stand test were measured at baseline, year 4, and year 14. The associations of DII score with the longitudinal changes of musculoskeletal parameters, and incidence of osteoporosis, sarcopenia, and fractures were examined by using general linear model, multinomial logistic regression model, and Cox proportional hazards regression model, respectively. After multiple adjustments, each tertile increase in DII score in men was associated with 0.37 (95% confidence interval [CI], 0.10–0.64) kg loss in grip strength and 0.02 (95% CI, 0.01–0.03) m/s loss in gait speed over 4 years. In men, the highest tertile of DII was associated with a higher risk of incident fractures, with adjusted and competing death adjusted hazard ratio (HR) (95% CI) of 1.56 (1.14–2.14) and 1.40 (1.02–1.91), respectively. In women, DII score was not significantly associated with any muscle-related outcomes or incidence of fracture, but a significant association between higher DII score and risk of osteoporosis at year 14 was observed, with the highest tertile of DII score having adjusted odds ratio (OR) (95% CI) of 1.90 (1.03–3.52). In conclusion, pro-inflammatory diet consumption promoted loss of muscle strength and physical function, and increased risk of fractures in older Chinese men. Pro-inflammatory diets had no significant association with muscle related outcomes but increased the long-term risk of osteoporosis in older Chinese women. © 2022 American Society for Bone and Mineral Research (ASBMR).  相似文献   
60.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号